1. Field of the Invention
This invention relates to a method of mounting, on a circuit board, a flat coil which is used with a motor, a deflecting yoke, a transformer and so forth.
2. Description of the Prior Art
Conventionally, a wound coil wherein a copper wire is wound in a number of layers is commonly used as a coil for a motor or for a deflecting yoke of a Braun tube. As miniaturization of appliances proceeds, so-called flat coils which are progressively reduced in thickness are developed and put into practical use.
As a coil for a deflecting motor, a sheet coil is used which is produced by forming a spiral pattern with a width of 50 microns or so by etching on copper foil laminated on an insulator sheet to construct a coil. Such sheet coil significantly contributes to reduction in thickness and in overall size of a motor.
On the other hand, such an idea has been proposed that copper foil to which an insulator film is applied is wound in layers and cut into round slices to produce flat coils. Such a flat coil has many advantages that it is superior in reduction in thickness and overall size of a motor, that it is easy to produce, and so forth.
By the way, the present applicant has proposed, in Japanese Patent Application No. 61-156135, a flat coil wherein a bar-like terminal portion or portions are disposed in an integral relationship on an outer peripheral face and/or an inner peripheral face of the flat coil and extend in a direction of the thickness of the flat coil, that is, in an axial direction of the flat coil.
In the flat coil, the bar-like terminals are provided in an integral relationship at a first portion and a last portion of a winding of copper foil which is wound in layers with such a thickness with which a desired characteristic is obtained, and a coiled portion of the flat coil is formed from a layered body consisting of the copper foil and a bonding agent layer laminated on the copper foil and serving as an insulator layer. Then, such flat coil is produced by soldering a conductor metal bar to one end of an original article (an article before it is cut into round slices) of the layered body, winding the original article around a predetermined take-up shaft and then cutting it into wound slices of a desired thickness or axial length.
With such a flat coil as described above, since metal parts which later make terminals are mounted, upon production of the flat coil, onto a soft and weak layered body of a thickness of about 55 microns or so constituted from copper foil and a bonding agent, a step or shoulder may be produced, upon soldering of the metal bar or upon winding of the layered body, due to a distortion or a difference in thickness to cause a break, cutting or the like of the copper foil.
Since the metal bars have no degree of freedom, a distortion or a wrinkle may take place on the layered body consisting of copper foil and so forth and may cause inaccuracy in dimension.
Further, even if the metal parts should not be soldered partially to the layered body, they may come behind the other metal bars, and consequently, it is often difficult to clearly confirm such defects.
Also when the flat coil is to be mounted onto a circuit board, solder material may not adhere well to a terminal in the form of a metal bar due to oxidation of a surface of the terminal and the terminal may not be soldered well to the layered body. The flat coil is thus disadvantageous in reliability in mounting thereof.